Stimulator systems and methods for selectively recruiting fascicles in hypoglossal nerve trunk

ABSTRACT

An electrode lead comprises a lead body, connector contacts affixed to the proximal end of the lead body, and a cuff body affixed to the distal end of the lead body. The cuff body is pre-shaped to transition from an unfurled state to a furled state, wherein the cuff body, when in the furled state has an inner surface for contacting a nerve and an overlapping inner cuff region and an outer cuff region. The electrode lead further comprise electrode contacts circumferentially disposed along the cuff body when in the furled state, such that at least one of the electrode contacts is located on the inner surface of the cuff body, and at least another of the electrode contacts is located between the overlapping inner and outer cuff regions. The electrode lead further comprises electrical conductors extending through the lead body respectively between the connector contacts and the electrode contacts.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims the benefit of priority to U.S.Provisional Application No. 62/522,266, filed on Aug. 30, 2017, which ishereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to systems and methods for the treatmentof obstructive sleep apnea (OSA), and more specifically for thetreatment of OSA by stimulating the hypoglossal nerve (HGN) trunk.

BACKGROUND

Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder thatis caused by the collapse of or increase in the resistance of thepharyngeal airway, often resulting from tongue obstruction. Theobstruction of the upper airway is mainly caused by reduced genioglossusmuscle activity during the deeper states of NREM sleep. Obstruction ofthe upper airway causes breathing to pause during sleep. Cessation ofbreathing causes a decrease in the blood oxygen saturation level, whichis eventually corrected when the person wakes up and resumes breathing.The long-term effects of OSA include high blood pressure, heart failure,strokes, diabetes, headaches, and general daytime sleepiness and memoryloss, among other symptoms.

OSA is extremely common, having a similar prevalence as diabetes orasthma. Over 100 million people worldwide suffer from OSA, with about25% of those being treated. Continuous Positive Airway Pressure (CPAP)is the usual established therapy for people who suffer from OSA. Morethan five million patients own a CPAP machine in North America, but manydo not comply with use of these machines, because they cover the mouthand nose and, hence, are cumbersome and uncomfortable.

The use of neurostimulators to open the upper airway has been exploredby several companies as a treatment for alleviating apneic events. Suchtherapy involves stimulating the nerve fascicles of the hypoglossalnerve (HGN) that innervate the intrinsic and extrinsic muscles of thetongue in a manner that prevents retraction of the tongue, which wouldotherwise close the upper airway during inspiration of the respiratorycycle.

ImThera Medical is currently in FDA clinical trials for a stimulatorsystem that is used to stimulate the trunk of the HGN with a nerve cuffelectrode. The stimulation system does not provide a sensor or sensing,and therefore, the stimulation delivered to the HGN trunk is notsynchronized to the respiratory cycle. Thus, the tongue and othermuscles that are innervated by nerve fascicles of the HGN trunk arestimulated irrespective of the respiratory cycle.

The rationale for this treatment method appears to be that it is enoughsimply to tone the tongue muscle and other nearby muscles, so that thetongue muscle does not retract in a manner that would cause obstructivesleep apnea. The belief is that it is not necessary to specificallytarget the protraction (i.e., anterior movement) of the tongue muscleand to synchronize the occurrence of tongue protraction when it is mostneeded, i.e., during inspiration. The nerve cuff electrode of theImThera Medical system has multiple electrode contacts helicallysurrounding the proximal part of the HGN nerve trunk. So, instead, eachelectrode contact delivers stimulation in a sequential order to the HGNtrunk. For example, if a three-electrode contact nerve cuff is used,electrode contact #1 stimulates, then stops, electrode contact #2stimulates, then stops, electrode contact #3 stimulates, then stops,then electrode contact #1 stimulates, then stops and so on. Since all ormost electrode contacts deliver stimulation, there is no selectionprocess to choose the best one or two electrode contact or contacts thatis finally used to deliver the best stimulation to alleviate sleepapnea.

However, because the HGN trunk contains nerve fascicles that innervatemuscles other than the muscle that extend the tongue, the ImtheraMedical method of stimulation at the HGN trunk does not just target thespecific protrusor tongue muscles, but may stimulate other tonguemuscles that are not targeted.

Another company, Inspire Medical Systems, Inc., does offer a stimulationsystem with a sensor, and therefore does attempt to time the onset ofstimulation to the breathing cycle. This system, which is FDA approvedfor sale in the United States since April 2010, uses a simple, bipolarelectrode (two electrode contacts only) within a nerve cuff electrodeand implants the electrode at the branch of the HGN that is responsiblefor protruding the tongue. A simple, two-electrode contact cuffelectrode can be used at the branch nerve, unlike the HGN trunk, becauseat the distal branch location, the nerve fascicles generally innervatethe specific tongue protrusor muscle and not other muscles.

However, implanting the electrode at a branch of the HGN takesadditional surgery time, which increases trauma to the patient andincreases the substantial expense of operating room time. By attachingthe nerve cuff electrode to the proximal section of the main trunk ofthe HGN, compared to placing the nerve cuff electrode at the more distalend of the HGN, it estimated that the surgical time will be reduced byapproximately one hour. Even more importantly, because the branch nerveis small and more difficult to isolate than the HGN trunk, implanting anerve cuff electrode at the branch site demands heightened expertisefrom the otolaryngologist/Ear Nose and Throat (ENT) surgeon orneurosurgeon, which significantly increases the chance for error andsurgical risks. Furthermore, because the distal location of the HGN hasa smaller diameter of nerves, and hence the required electrode contactsneed to be smaller, the smaller nerve cuff electrode may be moredifficult to manufacture.

Thus, it is desirable to implant the nerve cuff electrode at the trunkof the hypoglossal nerve. However, one must then deal with the fact thatthe target nerve fascicles are not easily isolated and stimulated, whileat the same time avoiding stimulating other fascicles in the same nervetrunk.

There, thus, remains a need for improved systems and methods forselectively recruiting only specific fascicles of the hypoglossal nerve,while minimizing the surgery time and effort required to implant theneurostimulation components in the patient.

SUMMARY

In accordance with a first aspect of the present inventions, anelectrode lead comprises an elongated lead body having a proximal endand a distal end, an array of connector contacts affixed to the proximalend of the lead body, and a biologically compatible, elastic,electrically insulative cuff body affixed to the distal end of the leadbody. The electrode lead further comprises an array of electrodecontacts (which may number at least three, and preferably at least six)circumferentially disposed along the cuff body when in the furled state,such that at least one of the electrode contacts is located on the innersurface of the cuff body, and at least another of the electrode contactsis located between the overlapping inner and outer cuff regions. Theelectrode lead further comprises a plurality of electrical conductorsextending through the lead body respectively between the array ofconnector contacts and the array of electrode contacts.

The cuff body is pre-shaped to transition from an unfurled state to afurled state, wherein the cuff body, when in the furled state has aninner surface for contacting a nerve and an overlapping inner cuffregion and an outer cuff region. The inner surface of the furled cuffbody may have a diameter in the range of 2.5 mm to 4.0 mm. In oneembodiment, only one of the electrode contacts is located between theoverlapping inner and outer cuff regions. In another embodiment, whenthe cuff body is in the unfurled state, a center-to-center spacing ofeach pair of adjacent ones of electrode contacts is equal to or lessthan twice a width of each electrode contact of the respective pair ofelectrode contacts.

In accordance with a second aspect of the present inventions, aneurostimulation system comprises the afore-described electrode lead,and a neurostimulator comprising a connector configured for receivingthe proximal contacts of the electrode lead, and stimulation circuitryconfigured for generating and delivering an electrical stimulation pulsetrain to at least one of the electrode contacts of the electrode lead.

In accordance with a third aspect of the present inventions, a method ofusing the afore-described electrode lead comprises maintaining the cuffbody in the unfurled state while placing the cuff body in contact withthe nerve (which may be, e.g., a trunk of a hypoglossal nerve (HGN)),and placing the cuff body from the unfurled state into the furled state,such that the cuff body wraps around the nerve. In one method, the sizeof the nerve allows the cuff body to wrap upon itself, such that the oneelectrode contact(s) are in contact with the nerve, and the otherelectrode contact(s) are between the overlapping inner and outer cuffregions without contacting the nerve. In another method, the size of thenerve may prevent the cuff body from wrapping upon itself, such that allof the electrode contacts are in contact with the nerve. When the cuffbody is wrapped around the nerve, a center-to-center spacing of eachpair of adjacent ones of electrode contacts is equal to or less thantwice a width of each electrode contact of the respective pair ofelectrode contacts. Still another method further comprises deliveringelectrical stimulation energy to one or more of the electrode contactsto stimulate the nerve. For example, the electrical stimulation energymay be delivered between a pair of adjacent ones of the electrodecontacts to stimulate the nerve in a bipolar mode.

In accordance with a fourth aspect of the present inventions, a methodof implanting an electrode lead in a patient is provided. The electrodelead comprises a biologically compatible, elastic, electricallyinsulative cuff body and an array of electrode contacts (which maynumber at least three, and preferably at least six) disposed along thecuff body. The method comprises wrapping the cuff body upon itselfaround a nerve (which may be, e.g., a trunk of a hypoglossal nerve (HGN)and may be in the range of 2.5 mm to 4.0 mm) of the patient, such thatthere exists an inner surface that contacts the nerve and an overlappinginner cuff region and an outer cuff region, at least one of theelectrode contacts being on the inner surface in contact with the nerve,and at least another of the electrode contacts being between the innerand outer overlapping regions of the cuff body without contacting thenerve. In one method, only one of the electrode contacts is locatedbetween the overlapping inner and outer cuff regions.

The cuff body may be pre-shaped to transition from an unfurled state toa furled state, in which case, the method may further comprisemaintaining the cuff body in the unfurled state while placing the cuffbody in contact with the nerve, and placing the cuff body from theunfurled state into the furled state, such that the cuff body wraps uponitself around the nerve. The cuff body may be wrapped around itselfaround the nerve, in which case, a center-to-center spacing of each pairof adjacent ones of electrode contacts is equal to or less than twice awidth of each electrode contact of the respective pair of electrodecontacts.

Other and further aspects and features of the invention will be evidentfrom reading the following detailed description of the preferredembodiments, which are intended to illustrate, not limit, the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of preferred embodimentsof the present invention, in which similar elements are referred to bycommon reference numerals. In order to better appreciate how theabove-recited and other advantages and objects of the present inventionsare obtained, a more particular description of the present inventionsbriefly described above will be rendered by reference to specificembodiments thereof, which are illustrated in the accompanying drawings.

Understanding that these drawings depict only typical embodiments of theinvention and are not therefore to be considered limiting of its scope,the invention will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a cut-away anatomical drawing of the head and neck areaillustrating the muscles that control movement of the tongue and thehypoglossal nerve and its branches that innervate these muscles;

FIG. 2 is a plan view of a stimulation system constructed in accordancewith one embodiment of the present inventions;

FIG. 3 is a block diagram of the internal components of an implantablepulse generator of the stimulation system of FIG. 2;

FIG. 4 is a perspective view of a lead electrode used in the stimulationsystem of FIG. 2;

FIG. 5 is a plan view of a nerve cuff electrode of the lead electrode ofFIG. 4, particularly shown in an unfurled state;

FIG. 6 is an end view of the nerve cuff electrode of FIG. 5,particularly shown in a furled state;

FIGS. 7a-7c are cross-sectional views of the nerve cuff electrode ofFIGS. 5 and 6 wrapped around differently sized HGN trunks;

FIG. 8 is a profile view of an alternative nerve cuff electrode of thelead electrode of FIG. 4, particularly shown in an unfurled state;

FIG. 9 is an end view of the nerve cuff electrode of FIG. 8,particularly shown in a furled state;

FIGS. 10a-10c are cross-sectional views of the nerve cuff electrode ofFIGS. 8 and 9 wrapped around differently sized HGN trunks; and

FIG. 11 is a flow diagram illustrating one method of implanting andfitting the stimulation system to a patient.

DETAILED DESCRIPTION

It is believed that obstruction to the upper airways is primarily causedby reduced genioglossus muscle activity during the deeper stages of NREMsleep. The present invention provides a system and method for moving theglossus (tongue) anteriorly using electrical stimulation to prevent theobstruction of the airway during sleep.

Referring first to FIG. 1, it is desirable to locate a nerve cuffelectrode 10 around a trunk 14 of a hypoglossal nerve (HGN) 12 forpurposes of stimulating the muscles that anteriorly move the tongue 16,and in particular, the fascicles of the HGN 12 that innervate the tongueprotrusor muscles, such as the genioglossus 18 and/or the geniohyoidmuscles 20. As shown, the nerve cuff electrode 10 is positioned on theHGN trunk 14 immediately before it branches out, and hence at a proximalposition 22 to the HGN branches 24. As briefly discussed above, theimplantation of the nerve cuff electrode 10 at this proximal position 22reduces the surgical time and effort, allows more surgeons to performthe surgery, reduces the risk and trauma to the patient, and reducesengineering design complexity and cost. However, it introduces theproblem of inadvertently stimulating other fascicles of the HGN trunk 14that innervate muscles in opposition to the genioglossus 18 and/or thegeniohyoid muscles 20, i.e., the tongue retractor muscles, e.g., thehyoglossus 26 and styloglossus muscles 28, as well as the intrinsicmuscles of the tongue 16.

Referring to FIG. 2, one embodiment of a stimulation system 50 thatselectively stimulates the fascicles of the trunk 14 of the HGN 12 thatinnervate the genioglossus 18 and/or the geniohyoid 20 muscles fortreating obstructive sleep apnea will now be described. The system 50generally comprises an implantable device 52, an electrode lead 54, aclinician programmer 56, and a patient programmer 58. The implantabledevice 52, or alternatively, an implantable pulse generator (“IPG”) orequivalently a “stimulator” can be implanted within a patient.

The electrode lead 54 comprises the aforementioned nerve cuff electrode10, a lead body 60 coupling the nerve cuff electrode 10 to theimplantable device 52 via a proximal lead connector 62 and acorresponding connector receptacle 64. Although the lead body 60 can bestraight, in the illustrated embodiment, the lead body 60 may have oneor more S-shaped sections in order to provide strain relief in order toaccommodate body movement at the location where the lead body 60 isimplanted. This strain relief feature is advantageous, since the leadbody 60 is intended to be implanted in a body location such as the neck,where the lead body 60 is subjected to frequent movement and stretching.Thus, the S-shape of the lead body 60 can help prevent damage to the HGNtrunk 14, resulting from sometimes, unavoidable pulling of the nervecuff electrode 10 as a result of neck movements. As will be described infurther detail, the nerve cuff electrode 10 comprises an array ofcircumferentially disposed electrode contacts.

Although only a single electrode lead 54 is shown in FIG. 2, someembodiments of the present system may have an IPG 52 having tworeceptacles 64 (not shown) for attaching two electrode leads, eachelectrode lead having a nerve cuff electrode 10. In such a two-electrodelead system, each nerve cuff electrode 10 can be implanted bilaterallyto each of the HGN trunks 14. However, it has been determined that onlya single nerve cuff electrode 10 implanted at the HGN trunk 14 on eitherside (unilaterally) can provide sufficiently effective stimulation toprotrude the tongue to control obstructive sleep apnea. A unilateralstimulation system is advantageous, since it is simpler in numbers ofcomponents used and requires only half the surgery to implant only asingle nerve cuff electrode 10, instead of two.

The IPG 52 comprises an outer case 66 for housing the electronic andother components (described in further detail below). In one embodiment,the outer case 66 is composed of an electrically conductive,biocompatible material, such as titanium, and forms a hermeticallysealed compartment wherein the internal electronics are protected fromthe body tissue and fluids. In some cases, the outer case 66 may serveas an electrode. As briefly discussed above, the IPG 52 furthercomprises a receptacle 64 to which the proximal end of the lead body 60mates in a manner that electrically couples the nerve cuff electrode 10to the internal electronics (described in further detail below) withinthe outer case 66.

Referring further to FIG. 3, the components and circuitry housed in theouter case 66 may comprise stimulation circuitry 68, control circuitry70, communication circuitry 72, memory 74, and sensing circuitry 76. Thestimulation circuitry 68, control circuitry 70, communication circuitry72, memory 74, and sensing circuitry 76 may be conveniently mounted on aprinted circuit board (PCB) (not shown).

In one embodiment, the sensing circuitry 76 comprises one or moresensor(s) (not shown) that are contained in the outer case 66, althoughin alternative embodiments, the sensor(s) may be affixed to the exteriorof the outer case 66. In other alternative embodiments, the sensor(s)can be positioned at a site remote from the IPG 52 coupled by aconnecting lead, e.g., as described in U.S. patent application Ser. No.15/093,495, filed on Apr. 7, 2016, entitled “Upper Airway StimulatorSystems for Obstructive Sleep Apnea,” which is expressly incorporatedherein by reference in its entirety.

The sensing circuitry 76 can detect physiological artifacts that arecaused by respiration (e.g., motion or ribcage movement), which areproxies for respiratory phases, such as inspiration and expiration or,if no movement occurs, to indicate when breathing stops. For example,the sensing circuitry 76 may sense movement of the thoracic cavityand/or detect changes in pressure/force in the thoracic cavity. Thus,the sensing circuitry 76 is configured for acquiring, conditioning, andprocessing signals related to respiration. The sensor(s) of the sensingcircuitry 76 can take the form of, e.g., inertial sensors (e.g.,accelerometers), bioimpedance sensors, pressure sensors, gyroscopes, ECGelectrodes, temperature sensors, GPS sensors, or some combinationthereof.

The stimulation circuitry 68 is coupled to the nerve cuff electrode 10via the lead body 60, and is configured for delivering stimulation tothe HGN trunk 14. The control circuitry 70 is coupled to the stimulationcircuitry 68 and controls when, and for how long, the stimulationcircuitry 68 applies stimulation to the HGN trunk 14. The controlcircuitry 70 may also control the intensity of the stimulation appliedby the stimulation circuitry 68 to the HGN trunk 14, e.g., by varyingthe amplitude, pulse width, or frequency of the stimulation. The controlcircuitry 70 may select the optimal electrode contact(s) of the nervecuff electrode 10 used for stimulating the HGN trunk 14, and inparticular, the electrode contacts that stimulate the fascicles of theHGN 14 innervating the genioglossus 18 or geniohyoid 20 protrusormuscles over the fascicles innervating the tongue retractor muscles,e.g., the hyoglossus 26 and styloglossus muscles 28, as well as theintrinsic muscles of the tongue 16, thereby preventing or alleviatingobstructive apneic events.

The memory 74 is configured for storing specific data gathered by thesensing circuitry 76 and programming instructions and stimulationparameters. The control circuitry 70 may recall the sensed data from thememory 74 and analyze it to determine when stimulation should bedelivered to synchronize the stimulation delivery with the respiratorycycle. In some embodiments, the sensor data may be analyzed to predictthe onset of the next inspiratory phase of the breathing cycle and todeliver stimulation right before, at, or slightly after the predictedonset of the inspiratory phase.

Thus, when the patient is in the inspiratory portion of the respiratorycycle—where the patient is breathing in or attempting to breath in, thecontrol circuitry 70 may condition the application of stimulation uponthe patient being in this inspiratory phase of respiration, therebycausing anterior displacement of the tongue, and causing the upperairway to remain un-obstructed during inspiration while sleeping. Thecontrol circuitry 70 causes the stimulation circuitry 68 to applystimulation in the form of a train of stimulation pulses during theseinspiratory phases of the respiratory cycle (or applying stimulationstarting slightly before the inspiration and ending at the end ofinspiration), and not the remainder of the respiration cycle, when allother conditions for stimulation are met. The train of stimulus pulsesmay be set to a constant time duration or it may be adaptive, meaningthat duration of the train of pulses can change dynamically based on apredictive algorithm that determines the duration of the inspiratoryphase of the respiratory cycle. The communication circuitry 72 isconfigured for wirelessly communicating transcutaneously (through thepatient's skin) with the clinician programmer 56 and patient programmer58 using radio frequency (RF) signals, e.g., via an Off The Shelf (OTS)inductive/Bluetooth/MICS radio link.

The clinician programmer 56 may be used to program the IPG 52 and querythe IPG 52 for status. For example, the clinician programmer 56 can beused to configure certain programs and processes used by the controlcircuitry 70 in the IPG 52 to determine when the stimulation pulses areto be delivered to electrode contacts of the nerve cuff electrode 10.The clinician programmer 56 can also be used to program specificstimulus parameters, such as stimulus pulse width, stimulus frequency,duration of a train pulses and pulse amplitude. The amplitude may beexpressed in current, for example, milliamperes, or it could beexpressed in volts, such as 0.3 volts. The choice between milliamperesor volts to express stimulus amplitude will depend on whether the designof the stimulation circuitry 68 provides stimulus pulses that areconstant voltage or constant current. Another important function of theclinician programmer 56 is the ability to select modes of stimulation.For example, the IPG 52 may operate in a monopolar stimulation mode(also sometimes referred to as a “unipolar” mode) and in a bipolarstimulation mode.

As used in this present disclosure, a monopolar stimulation mode meansthat one of the electrode contacts used is at least a portion of theouter case 66 that will function as an indifferent/anode electrode. Theindifferent electrode is part of the electrical circuit with at leastone electrode contact of the nerve cuff electrode 10 as theactive/cathode electrode contact that stimulates the HGN trunk 14.Generally, that part of the outer case 66 that is acting as theindifferent electrode does not stimulate any tissue or nerve, but merelyfunctions as a return electrode and may be a biocompatible, conductivemetal such as a titanium alloy, as discussed above.

A bipolar stimulation mode means, for purposes of this disclosure, thatthe outer case 66 is not part of the stimulation circuit. At least twoelectrode contacts of the nerve cuff electrode 10 must be selected andwill be part of the bipolar mode electrical stimulation circuit.Sometimes a stimulation circuit can have three or even more electrodecontacts functioning together. This may also be referred to as “bipolar”stimulation mode even though there are sometimes more than two activeelectrode contacts in the stimulation circuit. Sometimes athree-electrode contact system may be referred to as a tripolar circuit.For purposes of this disclosure and application, we will consider athree or more electrode-contact stimulation circuit (if it excludes theouter case 66) as variants of a bipolar stimulation mode and will beincluded as within a “bipolar” stimulation mode. The present stimulationsystem in its various embodiments, thus, may operate in either monopoloror bipolar stimulation modes.

In addition to choosing stimulation modes, the clinician programmer 56also can choose which electrode contacts of the nerve cuff electrode 10or the indifferent electrode of the outer case 66 are to be in thestimulation circuit. It may be possible, for example, to have threeelectrode contacts active simultaneously, where a middle electrodecontact is delivering a cathodic phase of stimulus pulse, while the twosurrounding electrode contacts are anodes in the anodic phase of thestimulus. The clinician programmer 56 may also be able to query thestatus of the IPG 52 for a number of status functions, such as batterystatus. Another query may be whether the IPG 52 is in an ON mode or anOFF mode. In the ON mode, the stimulation circuitry 68 within the IPG 52is enabled and stimulation pulses can be delivered via the selectedelectrode contact or contacts of the nerve cuff electrode 10. When thepatient is awake, the IPG may be placed automatically or by choice intothe OFF position or mode, and the stimulation circuitry 68 is notenabled and no stimulation can occur.

The patient programmer 58 offers more limited programming options thanthe clinician programmer 56. The patient programmer 58 may provide theoption to toggle the IPG 52 into the OFF mode or into the ON mode. Also,the stimulus pulse amplitudes may be adjusted for a limited range of upand down. Often the patient programmer 58, because of limitedfunctionality, may be in a package or form that is much smaller in sizethan the clinician programmer 56. The clinician programmer 56 andpatient programmer 58 may take the form of commercial electronic smartdevices on which there are installed customized applications forperforming the afore-described functions.

In an optional embodiment, the IPG 52 may have a magnetic reed switch(not shown) contained within the outer case 66 that can sense a magneticfield from an external magnet. An external magnet may be used to togglethe IPG 52 to the OFF position or alternatively to an ON position.Often, patients may need to undergo an MRI scan. A reed switch in theIPG 52 may make it MRI incompatible. In another embodiment, the IPG maycontain a sensor (not shown) that is sensitive to movement, such as aninertial sensor or an accelerometer, and can be toggled between an ONposition and an OFF position by tapping the implanted IPG 52, forexample, with the hand; for example, one tap to switch the IPG 52 froman ON position to an OFF position, and one tap to switch the IPG 52 froman OFF position to an ON position. In a particularly preferredembodiment, the IPG 52 can be toggled between an ON position and an OFFposition in response to multiple quick successive taps, as opposed to asingle tap, which may occur by accidental bumping and cause aninadvertent turn off of the IPG; for example, two taps to switch the IPG52 from an ON position to an OFF position, and two taps to switch theIPG 52 from an OFF position to an ON position. As a redundancy, thepatient programmer 58 or the clinician programmer 56 may also beconfigured to be able to toggle the IPG 52 from ON to OFF and from OFFto ON.

Referring further to FIGS. 4-6, the electrode lead 54 will now bedescribed in further detail. The proximal lead connector 62 comprises alinear array of connector contacts 78 a-78 f (in this case, six) forconnecting to the connector receptacle 64 of the IPG 52 when theproximal lead connector 62 is inserted into the connector receptacle 64.The nerve cuff electrode 10 comprises a nerve cuff body 80 that iscapable of substantially or completely encircling the HGN trunk 14, andan array of electrode contacts 82 a-82 f (in this case, six) affixed toinside of the cuff body 80, such that when the cuff body 80 encirclesthe HGN trunk 14, the electrode contacts 82 a-82 f are in contact withthe HGN trunk 14.

To facilitate selective activation of the fascicles of the HGN trunk 14that innervate the protrusor muscles, the electrode contacts 82 areaffixed to the cuff body 80 in a manner, such that when the cuff body 80encircles the HGN trunk 14, the electrode contacts 82 arecircumferentially disposed about the HGN trunk 14. In this case, theelectrode contacts 82 span the cuff body 80 circumferentially around theHGN trunk 14.

Although in some embodiments, the nerve cuff electrode 10 may beoperated in a monopolar stimulation mode, requiring that only oneelectrode contact 82 of the nerve cuff electrode 10 be activated at anygiven time, as will be described in further detail below, it isdesirable that the nerve cuff electrode 10 be operated in a bipolarstimulation mode, requiring that at least two electrode contacts 82 ofthe nerve cuff electrode 10 be activated at any given time. Although theexemplary nerve cuff electrode 10 comprises six electrode contacts 82a-82 f, other nerve cuff electrodes may have two to five electrodecontacts 82 or more than six electrode contacts 82. The preferred range,however, of the numbers of electrode contacts 82 on any particular nervecuff electrode is between three to eight electrode contacts 82, so as tosurround the circumference of the HGN trunk 14, and provide a sufficientnumber of independent electrode channels from which to select and torecruit the protrusor muscles without recruiting the retractor muscles.The connector contacts 78 a-78 f are respectively and independentlyelectrically coupled to the electrode contacts 82 a-82 f via electricalconductors (not shown), such that the electrode contacts 82 a-82 f maybe independently activated in either monopolar stimulation mode orbipolar stimulation mode. In the monopolar stimulation mode, one or moreof the electrode contacts 82 a-82 f will preferably be activated ascathode(s), whereas in the bipolar stimulation mode, one or more of theelectrode contacts 82 a-82 f will be activated as cathode(s), and one ormore other electrode contacts 82 a-82 f will be activated as anode(s).

The nerve cuff electrode 10 may be manufactured to be self-curling. Thematerial used for the electrode substrate can be typical implantableelectrode materials such as silicone, polyurethane or other materials,such as liquid crystal polymers. The material consistency of the formedcuff body 80 should be pliable enough to allow the clinician to unfoldthe cuff, as shown in FIG. 5, and placed around the HGN trunk 14 and tohave the nerve cuff electrode 10 curl back around itself, as shown inFIG. 6. The substrate material of the nerve cuff body 80, therefore,should have a memory property to the extent that it will tend to returnto its original curled shape. In one advantageous manufacturing process,the nerve cuff electrode 10, lead body 60, and proximal lead connector62 may be constructed of a flexible circuit, as described in U.S. patentapplication Ser. Nos. 15/634,057 and 15/634,134, both filed on Jun. 27,2017, and entitled “Nerve Cuff Electrodes Fabricated Using Over-MoldedLCP Substrates,” which are expressly incorporated by reference in theirentirety.

The nerve cuff electrode 10, as shown, will also have some give, so thatwhen the nerve swells during the inflammatory phase post-surgery, theinner lumen size of the nerve cuff electrode 10 can expand andaccommodate to the nerve swelling. This capability of self-adjustmentover time is important because once tissue has been dissected fromaround the nerve, there will be an inflammatory body response around thedamaged tissue and also in response to the presence of foreign matterthat may be introduced during the surgical implantation of the nervecuff electrode 10. Indeed, the nerve cuff electrode 10, itself, islikely seen as a foreign matter contributing to inflammation. Theinflammatory response may be ongoing over a period of months. Duringthis period, the nerve, itself, may swell up and increase substantiallyin diameter, perhaps up to 50% more than before the surgery. Once pastthis inflammatory response, the nerve diameter may then decrease insize, closer to its original diameter. If the inner lumen size of thenerve cuff electrode 10 does not adjust in size to accommodate theincrease in the nerve diameter, constriction of the target nerve canresult in traumatic cell damage and nerve death. Further detailsdescribing various self-expanding nerve cuff electrodes are set forth inU.S. patent application Ser. No. 15/967,332, filed on Apr. 30, 2018,entitled “Nerve Cuff Electrode Locking Mechanism,” and U.S. patentapplication Ser. No. 15/967,468, filed on Apr. 30, 2018, “Self-ExpandingNerve Cuff Electrode,” which claim the benefit of priority to U.S.Provisional Patent Application Ser. No. 62/500,080, filed on May 2,2017, entitled “Nerve Cuff Electrode Locking Mechanism,” and U.S.Provisional Patent Application Ser. No. 62/500,091, filed on May 2,2017, entitled “Self-Expanding Nerve Cuff Electrode,” all of which areexpressly incorporated herein by reference in their entirety.

As briefly discussed above, it is desirable to operate the nerve cuffelectrode 10 in a bipolar mode in order to facilitate selectiverecruitment of the fascicles 15 in the HGN trunk 14. That is, monopolarstimulation results in a more diffuse electrical field that will tend torecruit most fascicles 15 in the HGN trunk 14, whereas bipolarstimulation results in a more specific and confined electrical fieldthat will tend to recruit less non-targeted fascicles 15 in the HGNtrunk 14. Thus, the fascicles 15 in the HGN trunk 14 that innervate thetongue protrusor muscles can be more selectively activated via bipolarstimulation. Because the electrode contacts 82 will circumferentiallysurround the HGN trunk 14, the electrical field generated by the nervecuff electrode 10 in the bipolar stimulation mode can be selectivelysteered around the HGN trunk 14 to recruit the desired fascicles 15within the HGN trunk 14. It is further noted that, because the fascicles15 innervating the tongue protrusor muscles are peripherally located atthe proximal position 20 to the HGN branches 18, it is desirable thatadjacent electrode contacts 82 can be activated in the bipolararrangement, such that the electrical field extends only peripherallyinto the HGN trunk 14. Thus, with reference to FIG. 6, it may bedesirable to activate electrode contact pair 82 a-82 b, electrodecontact pair 82 b-82 c, electrode contact pair 82 c-82 d, electrodecontact combination 82 d-82 e, electrode contact combination 82 e-82 f,or electrode combination 82 f-82 a. As shown in FIG. 6, electrodecombination 82 a-82 b are shown to be activated to create a confinedbipolar electrical field therebetween that recruits one or more of theperipherally located fascicles 15 a, as opposed to recruiting thecentrally located fascicles 15 b. Of course, any of the other electrodecombinations can be operated in a bipolar manner to recruit otherperipherally located fascicles 15 a. The first one of the electrodecontacts 82 in the combination can be a cathode, and the second one ofthe electrode contacts 82 in the combination can be an anode, or viceversa.

Notably, the strongest electrical field generated by the nerve cuffelectrode 10 will be beneath an active an active electrodecontact/cathode. Thus, in order to effectively employ bipolarstimulation, the nerve cuff electrode 10 may have the following designconstraint: L≤2 W, where W is the width of each electrode contact 82,and L is the center-to-center distance between two adjacent electrodecontacts 82, as illustrated in FIG. 5. This constraint is based on thecommercial needs in neuromodulation therapies to cover the most distancewith spatial separations L and using the fewest number of electrodecontacts 82. The width of the electrode contacts 82 will typically bebased on the particular neural element that will be stimulated or thesize of the cuff body 80, or a combination thereof, and will set thestrength ranges of the electric fields generated by the nerve cuffelectrode 10. As the center-to-center distance L exceeds the L≤2 Wdesign constraint, the electric field generated by a bipolar pair ofelectrode contacts 82 quickly starts to resemble a monopolar electricfield as if there as a remote anode (unless there is a dramatic increasein the electric field amplitude). The ability of perform currentsteering between two or more adjacent electrode contacts 82 alsoweakens. In contrast, if adjacent electrode contacts 82 are too close ortouching each other, there may be bleeding of electrical fields acrossthe active contacts 82 at a higher amplitude, thereby creating a shortthat changes the ability to spatially select fascicles. Thus, it isimportant that the center-to-center distance L between adjacentelectrode contacts 82 and the width W of the electrode contacts 82 beconstrained.

However, because the size of the HGN 12 varies within the humanpopulation (e.g., between 2.5 mm and 4.00 mm), the effective distancebetween the electrode contacts 82 a, 82 f of a nerve cuff electrode 10when wrapped around a HGN trunk 14 may vary with the size of the HGNtrunk 14, thereby requiring nerve cuff electrodes to be made indifferent sizes.

For example, as shown in FIGS. 7a-7c , the distance between theelectrode contacts 82 a, 82 f (shown to have widths W of 0.8 mm) willincrease as the diameter of the HGN trunk 14 increases from 3.0 mm to3.8 mm. However, it is desirable that the distance between the electrodecontacts 82 a, 82 f be maintained in accordance with the L≤2 W designconstraint to ensure that bipolar stimulation using the electrodecontacts 82 a, 82 f is effective. As illustrated in FIG. 7a , thedistance between electrode contacts 82 a, 82 f complies with the L≤2 Wdesign constraint. That is, the center-to-center distance L_(a-f)between the electrode contacts 82 a, 82 f is shown to be 0.7 mm when thediameter of the HGN trunk 14 is 3.0 mm, thereby complying with the L≤2 Wdesign constraint (0.7 is less than (2×0.8). However, as illustrated inFIGS. 7b and 7c , the distance between electrode contacts 82 a, 82 fviolates the L≤2 W design constraint, thereby causing the nerve cuffelectrode 10 to have a “dead spot” between the electrode contacts 82 a,82 f that would not be effective in bipolar stimulation. That is, thecenter-to-center distance L_(a-f) between the electrode contacts 82 a,82 f is shown to be 2.0 mm when the diameter of the HGN trunk 14 is 3.4mm, thereby violating the L≤2 W design constraint (2.0 is greater than(2×0.8)), and the center-to-center distance L_(a-f) between theelectrode contacts 82 a, 82 f is shown to be 3.3 mm when the diameter ofthe HGN trunk 14 is 3.8 mm, thereby violating the L≤2 W designconstraint (3.8 is greater than (2×0.8)).

In order to prevent the occurrence of a blind spot between the electrodecontacts 82, and because there is variation in HGN nerve diameters, inthe operating room, many different sizes of nerve cuff electrodes wouldneed to be readily available to the surgeon. For example, in order tocover the range of HGN nerve sizes in the general population, at leastfive different sizes of nerve cuff electrodes would have to befabricated and supplied to the surgeon in the operating room. Unusednerve cuff electrodes, opened during surgery, may need to be discarded,thereby increasing the cost of the surgical procedure. Furthermore, asurgeon will have to measure every HGN size to determine the right sizeof the nerve cuff electrode to be placed onto the HGN, which increasesthe time in the operating room. Measuring the HGN size requires verydelicate work and can be quite subjective as well. Hence, the process isnot only cumbersome and prone to error, but most importantly, poses therisk of damaging the HGN during the process to precisely measure theHGN.

In accordance with the present inventions, one embodiment of a nervecuff electrode 10′ accommodates a large range of HGN sizes withoutcreating blind spots, thereby eliminating the need to fabricatedifferently sized nerve cuff electrodes. In this embodiment, the arrayof electrode contacts 82 is disposed on the cuff body 80, and the cuffbody 80 is pre-shaped to, in the absence of an external force,transition from an unfurled state (FIG. 8) to a furled state (FIG. 9).In one embodiment, the cuff body 80 will automatically transition fromthe unfurled state to the furled state in response to merely removing anexternal force from the cuff body 80. In another embodiment, the cuffbody 80 is pre-shaped to curve in two orthogonal directions (along alateral axis and a longitudinal axis), such that the cuff body 80 has abi-stable structure. In this embodiment, an external force must beexerted on the cuff body 80 to transition it between the unfurled andfurled state. Further details describing a bi-stable cuff body 80 areset forth in U.S. patent application Ser. No. 15/634,057, filed on Jun.27, 2017, entitled “Nerve Cuff Electrodes Fabricated Using Over-MoldedLCP Substrates,” and Ser. No. 15/634,134, filed on Jun. 27, 2017,entitled “Nerve Cuff Electrodes Fabricated Using Over-Molded LCP,” whichhave been expressly incorporated by reference.

In the unfurled state, all pairs of adjacent electrode contacts 82(i.e., 82 a-82 b, 82 b-82 c, 82 c-82 d, 82 d-82 e, and 82 e-82 f)nominally comply with L≤2 W design constraint. In the furled state, thecuff body 80 has an inner surface 84 capable of contacting the HGN trunk14, as well as an overlapping inner cuff region 86 a and outer cuffregion 86 b. Furthermore, when the cuff body 80 is in the furled state,the electrode contacts 82 are circumferentially disposed along the cuffbody 80, such that at least one of the electrode contacts 82 is locatedon the inner surface 84 of the cuff body 80, and at least another one ofthe electrode contacts 82 is disposed between the overlapping inner andouter cuff regions 86 a, 86 b. Since the nominal distances between therespective pairs of adjacent electrode contacts 82 a-82 b, 82 b-82 c, 82c-82 d, 82 d-82 e, and 82 e-82 f are fixed and therefore will notchange, it is expected that these distances will comply with the L≤2 Wdesign constraint when the cuff body 80 is in the furled state, and willtherefore, provide effective bipolar stimulation as long as therespective electrode contact pairs are in contact with the HGN trunk 14.However, as will be described in further detail below, the distancebetween the electrode contact 82 a and the electrode contact 82 f willvary in accordance with the diameter of the HGN trunk 14.

Although only one electrode contact, and in this case the electrodecontact 82 f, is shown as being disposed between the overlapping innerand outer cuff regions 86 a, 86 b in FIG. 9, more than one electrodecontact 82 may be disposed between the overlapping inner and outer cuffregions 86 a, 86 b. The number of electrode contacts 82 that aredisposed between the overlapping inner and outer cuff regions 86 a, 86 bwhen the cuff body 80 is in the furled state can be selected byselecting the number of electrode contacts 82 and/or the nominalcenter-to-center distances between adjacent electrode contacts 82. Thatis, the number of electrode contacts 82 that are disposed between theoverlapping inner and outer cuff regions 86 a, 86 b will tend toincrease as the number of electrode contacts 82 increases and/or thenominal center-to-center distance between adjacent electrode contacts 82increases. In the example shown in FIGS. 8 and 9, the number ofelectrode contacts 82 relative to the embodiment shown in FIGS. 5 and 6remains the same (i.e., six total), but the nominal center-to-centerdistance L between adjacent electrode contacts 82 have been increased,resulting in one electrode contact 82 being disposed between theoverlapping inner and outer cuff regions 86 a, 86 b when the cuff body80 is in the furled state. Of course, if the nominal center-to-centerdistance L between adjacent electrode contacts 82 is increased and/orthe number of electrode contacts 82 is increased, additional electrodecontacts 82 may be disposed between the overlapping inner and outer cuffregions 86 a, 86 b when the cuff body 80 is in the furled state.

Advantageously, the nerve cuff electrode 10′ is capable of being usedwith differently sized HGN trunks 14 while still complying with the L≤2W design constraint for all pairs of adjacent electrode contacts 82 thatare in contact with the HGN trunk 14. In particular, the extent that thecuff body 80 furls will adjust in accordance with the diameter of theHGN trunk 14, such that one of the set of electrode contacts 82 at theend of the array of electrode contacts 82 (in this case, either theelectrode contact 82 e or the electrode contact 82 f) will be in contactwith the HGN trunk 14 adjacent to the next electrode contact 70 adjacentto this electrode contact 70 (in this case, the electrode contact 82 eor the electrode contact 70 d) in compliance with the L≤2 W designconstraint.

For example, as shown in FIGS. 10a-10c , for smaller diameter HGN trunks14, the electrode contact 82 f will be located between the overlappinginner and outer cuff regions 86 a, 86 b, but the next electrode contact82 e will be in contact with the HGN trunk 14 in a bipolar relationshipwith the electrode contact 82 in compliance with the L≤2 W designconstraint. However, as the diameter of the HGN trunk 14, the cuff body80 will partially unfurl, causing the electrode contact 82 f to bedisplaced from between the overlapping inner and outer cuff regions 86a, 86 b to a position that is contact with the HGN trunk 14 in a bipolarrelationship with the electrode contact 82 in compliance with the L≤2 Wdesign constraint.

Thus, as illustrated in FIG. 10a , the electrode contact 82 f is betweenthe overlapping inner and outer cuff regions 86 a, 86 b, such that itdoes not contact the HGN trunk 14. However, the electrode contact 82 eis in contact with the HGN trunk 14 in a bipolar relationship withelectrode contact 82 a. The center-to-center distance L_(a-e) betweenthe electrode contacts 82, 82 e is shown to be 0.7 mm when the diameterof the HGN trunk 14 is 3.0 mm, thereby complying with the L≤2 W designconstraint (0.7 is less than (2×0.8)). As illustrated in FIG. 10b , asthe cuff body 80 partially unfurls due to the increased diameter of theHGN trunk 14, the electrode contact 82 f is not between the overlappinginner and outer cuff regions 86 a, 86 b, but instead is in contact withthe HGN trunk 14 in a bipolar relationship with electrode contact 82.The center-to-center distance L_(a-f) between the electrode contacts 82a, 82 f is shown to be 0.7 mm when the diameter of the HGN trunk 14 is3.4 mm, thereby complying with the L≤2 W design constraint (0.7 is lessthan (2×0.8)). As illustrated in FIG. 10c , as the cuff body 80 furtherpartially unfurls due to the increased diameter of the HGN trunk 14, thecenter-to-center distance L_(a-f) between the electrode contact 82 f andthe electrode contact 82 a increases. However, the center-to-centerdistance L between the electrode contacts 82 a, 82 f is shown to be 1.6mm when the diameter of the HGN trunk 14 is 3.8 mm, thereby complyingwith the L≤2 W design constraint (1.6 is equal to (2×0.8)).

It should be appreciated that if it is desired to increase the range ofdiameter size of the HGN trunk 14 with which the nerve cuff electrode10′ used, such nerve cuff electrode 10′ can be designed, such that morethan one electrode contact 82 will be disposed between the overlappinginner and outer cuff regions 86 a, 86 b for the smallest designeddiameter of the HGN trunk 14. For example, the number of electrodecontacts 82 may be increased (e.g., from six to seven) or the cuff body80 may be pre-shaped to have a smaller diameter in the absence of anexternal force.

Having described the structure and function of the nerve cuff electrode10′, one method 100 of implanting the nerve cuff electrode 10′ in apatient will now be described with reference to FIG. 11. First, the cuffbody 80 is maintained in the unfurled state (FIG. 8) while placing thecuff body 80 in contact with the HGN trunk 14 (step 102). For example,the unfurled cuff body 80 may be placed underneath the HGN trunk 14. Thecuff body 80 may be maintained in the unfurled state by, e.g., applyingan external force to the cuff body 80 to prevent it from transitioningto the furled state, or if the cuff body 80 has a bi-stable structure,the cuff body 80 may be maintained in the unfurled state by not applyingan external force to transition it to the furled state.

Next, the cuff body 80 is transitioned from the unfurled state into thefurled state, such that the cuff body 80 wraps around the HGN trunk 14(step 104). The cuff body 80 may be placed from the unfurled state intothe furled state by, e.g., merely removing the external force from thecuff body 80, such that the cuff body 80 automatically transitions fromthe unfurled state to the furled state, or if the cuff body 80 has abi-stable structure, an external force may be exerted on the cuff body80 to transition it from the unfurled state to the furled state.

If the size of the HGN trunk 14 is relatively small, the cuff body 80may wrap upon itself, as shown in FIG. 10a . In this case, there existsan inner surface 84 that contacts the HGN trunk 14 and an overlappinginner cuff region 86 a and an outer cuff region 86 b, and the electrodecontacts 82 that are on the inner surface 84 of the cuff body 80 iscontact with the HGN trunk 14, and at least another of the electrodecontacts 82 is between the inner and outer overlapping regions 86 a, 86b of the cuff body 80 without contacting the HGN trunk 14. If the sizeof the HGN trunk 14 is relatively large, the cuff body 80 may beprevented from wrapping upon itself, as shown in FIGS. 10b and 10c . Inthis case, all electrode contacts 82 will be in contact with the HGNtrunk 14. In all cases, the center-to-center spacing L of eachrespective pair of adjacent electrode contacts 82 is equal to or lessthan twice the width W of each electrode contact 82 of the respectivepair of adjacent electrode contacts 82.

Next, the IPG 52 is implanted within the patient (step 106), and theproximal lead connector 62 is mated with the receptacle 64 of the IPG 52(step 108). Next, electrical stimulation energy is delivered to a pairof adjacent ones of the electrode contacts 82 to stimulate the HGN trunk14 in a bipolar mode, and preferably, the fascicles of the HGN trunk 14innervating the tongue protrusor muscles (step 110). Step 110 can berepeated for different pair of electrode contacts 82 to find the optimalelectrode contact pairs in a fitting procedure. Lastly, the IPG 52 isprogrammed with the optimal electrode contact pair(s) using theclinician programmer 56 (step 112).

Although particular embodiments of the present inventions have beenshown and described, it will be understood that it is not intended tolimit the present inventions to the preferred embodiments, and it willbe obvious to those skilled in the art that various changes andmodifications may be made without departing from the spirit and scope ofthe present inventions. Thus, the present inventions are intended tocover alternatives, modifications, and equivalents, which may beincluded within the spirit and scope of the present inventions asdefined by the claims.

What is claimed is:
 1. An electrode lead, comprising: an elongated leadbody having a proximal end and a distal end; an array of connectorcontacts affixed to the proximal end of the lead body; a biologicallycompatible, elastic, electrically insulative cuff body affixed to thedistal end of the lead body, the cuff body pre-shaped to transition froman unfurled state to a furled state, wherein the cuff body, when in thefurled state has an inner surface for contacting a nerve and anoverlapping inner cuff region and an outer cuff region; an array ofelectrode contacts circumferentially disposed along the cuff body whenin the furled state, such that at least one of the electrode contacts islocated on the inner surface of the cuff body, and at least another ofthe electrode contacts is located between the overlapping inner andouter cuff regions; and a plurality of electrical conductors extendingthrough the lead body respectively between the array of connectorcontacts and the array of electrode contacts.
 2. The electrode lead ofclaim 1, wherein only one of the electrode contacts is located betweenthe overlapping inner and outer cuff regions.
 3. The electrode lead ofclaim 1, wherein the inner surface of the furled cuff body has adiameter in the range of 2.5 mm to 4.0 mm.
 4. The electrode lead ofclaim 1, wherein the array of electrode contacts numbers at least three.5. The electrode lead of claim 1, wherein the array of electrodecontacts numbers at least six.
 6. The electrode lead of claim 1,wherein, when the cuff body is in the unfurled state, a center-to-centerspacing of each pair of adjacent ones of electrode contacts is equal toor less than twice a width of each electrode contact of the respectivepair of electrode contacts.
 7. A neurostimulation system, comprising:the electrode lead of claim 1; and a neurostimulator comprising aconnector configured for receiving the proximal contacts of theelectrode lead, and stimulation circuitry configured for generating anddelivering an electrical stimulation pulse train to at least one of theelectrode contacts of the electrode lead.
 8. A method of using theelectrode lead of claim 1, comprising: maintaining the cuff body in theunfurled state while placing the cuff body in contact with the nerve;and placing the cuff body from the unfurled state into the furled state,such that the cuff body wraps around the nerve.
 9. The method of claim8, wherein the size of the nerve allows the cuff body to wrap uponitself, such that the at least one electrode contact is in contact withthe nerve, and the at least other electrode contact is between theoverlapping inner and outer cuff regions without contacting the nerve.10. The method of claim 8, wherein the size of the nerve prevents thecuff body from wrapping upon itself, such that all of the electrodecontacts are in contact with the nerve.
 11. The method of claim 8,wherein the nerve is a trunk of a hypoglossal nerve (HGN).
 12. Themethod of claim 8, wherein the array of electrode contacts numbers atleast three.
 13. The method of claim 8, wherein the array of electrodecontacts numbers at least six.
 14. The method of claim 8, wherein, whenthe cuff body is wrapped around the nerve, a center-to-center spacing ofeach pair of adjacent ones of electrode contacts is equal to or lessthan twice a width of each electrode contact of the respective pair ofelectrode contacts.
 15. The method of claim 8, further comprisingdelivering electrical stimulation energy to one or more of the electrodecontacts to stimulate the nerve.
 16. The method of claim 8, furthercomprising delivering electrical stimulation energy between a pair ofadjacent ones of the electrode contacts to stimulate the nerve in abipolar mode.
 17. A method of implanting an electrode lead in a patient,the electrode lead comprising a biologically compatible, elastic,electrically insulative cuff body and an array of electrode contactsdisposed along the cuff body, the method comprising: wrapping the cuffbody upon itself around a nerve of the patient, such that there existsan inner surface that contacts the nerve and an overlapping inner cuffregion and an outer cuff region, at least one of the electrode contactsbeing on the inner surface in contact with the nerve, and at leastanother of the electrode contacts being between the inner and outeroverlapping regions of the cuff body without contacting the nerve. 18.The method of claim 17, wherein the cuff body is pre-shaped totransition from an unfurled state to a furled state, the method furthercomprising: maintaining the cuff body in the unfurled state whileplacing the cuff body in contact with the nerve; and placing the cuffbody from the unfurled state into the furled state, such that the cuffbody wraps upon itself around the nerve.
 19. The method of claim 17,wherein only one of the electrode contacts is located between theoverlapping inner and outer cuff regions.
 20. The method of claim 17,wherein the diameter of the nerve is in the range of 2.5 mm to 4.0 mm.21. The method of claim 17, wherein the nerve is a trunk of ahypoglossal nerve (HGN).
 22. The method of claim 17, wherein the arrayof electrode contacts numbers at least three.
 23. The method of claim17, wherein the array of electrode contacts numbers at least six. 24.The method of claim 17, wherein, when the cuff body is wrapped arounditself around the nerve, a center-to-center spacing of each pair ofadjacent ones of electrode contacts is equal to or less than twice awidth of each electrode contact of the respective pair of electrodecontacts.